Auxin herbicides have proven to be effective and highly beneficial for control of unwanted plants. Auxin herbicides include 3,6-dichloro-2-methoxybenzoic acid (dicamba); 2,4-dichlorophenoxyacetic (2,4-D); 4-(2,4-dichlorophenoxy)butanoic acid (2,4-DB); 2-(2,4-dichlorophenoxy)propanoic acid (dichloroprop); 2-(4-chloro-2-methylphenoxy)acetic acid (MCPA); 4-(4-chloro-2-methylphenoxy)butanoic acid (MCPB); 4-amino-3,6-dichloro-2-pyridinecarboxylic acid (aminopyralid); 3,6-dichloro-2-pyridinecarboxylic acid (clopyralid); 2-[(4-amino-3,5-dichloro-6-fluoro-2-pyridinyl)oxy]acetic acid (fluroxypyr); [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid (triclopyr); 2-(4-chloro-2-methylphenoxy)propanoic acid (mecoprop); 4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid (picloram); 3,7-dichloro-8-quinolinecarboxylic acid (quinclorac); 6-amino-5-chloro-2-cyclopropyl-4-pyrimidinecarboxylic acid (aminocyclopyrachlor); agriculturally acceptable salts or other derivatives of any of these herbicides; racemic mixtures and resolved isomers thereof; and mixtures thereof. Generally, auxin herbicides mimic or act like natural auxin plant growth regulators. Auxin herbicides appear to affect cell wall plasticity and nucleic acid metabolism, which can lead to uncontrolled cell division and growth. The injury symptoms caused by auxin herbicides include epinastic bending and twisting of stems and petioles, leaf cupping and curling, and abnormal leaf shape and venation.
Off-site movement is sometimes associated with auxin herbicides. Under some application conditions, auxin herbicides can volatilize into the atmosphere and migrate from the application site to adjacent crop plants or non-target plants where contact damage can occur. Typical symptoms of injury to crop plants include leaf cupping, leaf malformation, leaf necrosis, terminal bud kill and/or delayed maturity.
Accordingly, there remains a need for an economic, convenient solution that reduces volatility of auxin herbicides. A solution that does not require costly modifications to existing herbicide production or formulation processes would be beneficial. Furthermore, a solution that can be used with conventional auxin herbicide formulations and that can be practiced in field during preparation of auxin herbicide-containing herbicide mixtures (e.g., tank mixes) would be advantageous.
Further, with the development of transgenic crop plants including stacked traits, such as dicamba tolerance, 2,4-D tolerance, and glyphosate tolerance traits, herbicidal mixtures containing an auxin herbicide and a co-herbicide are particularly beneficial and convenient for control of unwanted plants. However, addition of a co-herbicide to auxin herbicidal mixtures has been known to affect the volatility of the auxin herbicide and increase off-site movement of the herbicide. For example, tank mixing of auxin herbicides such as dicamba or 2,4-D with certain co-herbicides, such as glyphosate, has been known to exacerbate problems associated with volatility of the auxin herbicide. Accordingly, there remains a need for an economic, convenient solution that reduces or controls the negative effects on auxin volatility resulting from the addition of a co-herbicide.
As will be clear from the disclosure that follows, these and other benefits are provided by the present invention.